As you will see later in the module, the bicycle
frame geometry significantly affects how the frame members are
loaded. This applet allows you to redesign the shape of the bicycle by
dragging on the joints. As you do so the x and y coordinates of the
joints (shown) will be updated. In doing so, you will also be
affecting the length of the tube members.
Drag the joints so that the top tube (between the seat and the
handlebars) is horizontal (any length is OK). What is similar between
the coordinates of the two joints? Suppose you were constructing a
bike based on your design, what length of steel would you need for the
top tube?
Now move the joint nearest the handlebars upwards a bit so that the
top tube is no longer vertical. Now what is the length of the top
tube? It is not as easy to determine, perhaps, as it was when the tube
was horizontal. Use the concept of position
vectors to help you determine it.
In addition find the current lengths of the other tube members. Once
again, check your answers with the applet.
Once you have verified the tube member lengths for the current frame
shape, continue dragging the joints on the frame and see if you can
understand how changing the joint coordinates changes the tube
lengths.